Railway signaling system



Sept. 30, 1958 c. D. lHRlG 2,854,566

RAILWAY SIGNALING SYSTEM Filed Aug. 24, 1954 s Sheets-Sheet 1 y Traffic Conditions in Advance oi Signal 45 INVENTOR. Ullli'iord D. [brig BY LU W HIS LTTUHNFJY Governed b Fly 1a.

Sept. 30, 1958 c. D. IHRIG RAILWAY SIGNALING SYSTEM 3 Sheets-Sheet 2 Filed Aug. 24, 1954 INVENTOR. 1b flliflord Blbrig L0. L. W

H15 A T TOR/YE Y Sept. 30, 1958 c. D. IHRIG RAILWAY SIGNALING SYSTEM 3 Sheets-Sheet 3 Filed Aug. 24, 1954 Governed by Traii'w 103G Gondiiimzs in Advance of Signal log INVENTOR. C'lz'liani 0 [brig BY w k. W

HIS ATTORNEY States Patented Sept. 30, 1958 TCQ RAILWAY SIGNALING SYSTEM Application August 24, 1954-, Serial No. 451,744

Claims. ((31. 24626) My invention relates to railway signaling systems, and particularly to railway signaling systems of the type in which the direction of trafiic through a stretch of railway track is established by means of a traffic locking circuit which may be arranged to be supplied with energy of one polarity or the other from one or both ends of the circuit, to thereby position polar trafiic relays at various locations throughout the stretch for governing the operation of wayside signals in accordance with the direction of traflic movement. Although not limited thereto, my invention is particularly applicable to railway signaling systems of a type employing one pair of line wires for the traffic governing circuits, with a second pair of line wires for governing the operation of the wayside signals, the signal control line circuits being reversibly energized at opposite ends to control the signals in accordance with the direction of traliic movement.

In systems of the type described, it is essential to check that the stretch is unoccupied and the wayside signals governing entrance into the stretch at each end are displaying stop aspects before a reversal of tratfic movement can take place. This is to insure that no train is occupying or has permission to occupy the stretch at the time that traflic reversal takes place; otherwise a condition could arise in which, after a train moving in one direction entered the stretch, the direction of traflic could be reversed and a signal cleared for a train to enter the stretch from the opposite direction.

Accordingly, an object of my invention is to provide a novel and improved traflic locking system for a railway signaling system, in which the unoccupied condition of the stretch of track involved and the signals at each end of the stretch for permitting tralfic movements into the stretch are checked to insure that these signals are displaying a stop aspect, before a reversal of trafiic can be made.

Another object of my invention is to provide an improved arrangement for a trattic locking circuit in a railway signaling system in which trafiic stick relays are provided which are governed by traffic relays operated from a polarized traffic circuit, the trafiic stick relays in turn governing the control of the Wayside signal circuits.

Still a further object of my invention is to provide an improved railway signaling system which will not permit the signal governing moves into the single track stretch at either end of the stretch to clear when trafiic is being changed in direction until a check has been made at the opposite end of the stretch that the traffic relay at that end has responded and that the opposing signal is displaying a stop aspect.

A further object of my invention is to provide a new and improved railway signaling system employing a polarized traflic locking circuit and a polarized signal control circuit, in which polar trafiic relays energized from the polarized traflic control circuit are checked for proper positioning before the associated polarized signal control circuits can be energized to permit trafiic movemerits into the stretch of track protected by the signaling system.

In practicing'my invention, I provide, in a system of the type described for governing the movement of trains through a stretch of single track, a set of wayside signals for each direction of tratlic and a signal control line circuit extending between each of the signal locations located throughout the stretch. Each signal control'line circuit, of the two-wire type, is arranged to be selectively energized at one end or the other, with energy of a first or second relative polarity, according to traffic conditions in advance of the particular section with which the line circuit is associated. At each end of each signal control line circuit, there is provided a signal control line relay, arranged to be connected at times to the signal line circuit to be responsive to the energy supplied thereto. This signal control line circuit is governed by the contacts of relays which check the occupancy'of the associated track section or sections, so that the line circuit is interrupted at any time that the section or sections between signal locations are occupied by a train. The selection of the direction of energization of each signal control line circuit is governed by the contacts of a trafiic repeater relay, which in turn is governed by the contacts of polar traffic relays, one for each location, which are included in a polarized traflic control circuit, which may be energized from one or both ends of the traflic circuit, depending upon the conditions under which the circuit is to be used.

The traflic control circuit is of the conventional type in which a pair of line wires, extending between the signal locations in the stretch to which the system is applied,"

have included in series therewith the windings of polar traffic relays, one for each signal location, and contacts of the relays which check the occupancy of the various sections into which the stretch is divided. The line circuit may be arranged to be energized either from one end or from both ends, but is herein shown as energized only from one end, in such manner that the polarity of the energy supplied thereto reflects the direction in which traffic is to move through the stretch, and accordingly positions the polar contacts of the polar traflic relays.

The polar trafiic relays at the entering ends of the single track stretch provided with a signaling system in accordance with my invention control trafiic repeater relays. Each repeater relay is governed by the traffic relay located at that end of the stretch in such manner that the traffic repeater relay can be picked up only when the associated polar traffic relay has its contacts operated in the direction to permit trains to leave the stretch from that end, and when a check shows that the entering signal governing traflic movements at that end of the stretch is at stop. 7

At intermediate locations throughout the stretch, a pair of ti afiic repeating relays is provided, governed by contacts of a polar traffic relay in such manner that a trafiic repeater relay can pick up only if the signal control line circuit for the section in advance indicates that the section is unoccupied, and if the trafiic repeater relay for the opposite direction of movement is deenergized.

As pointed out previously, the contacts of the tratiic repeater relays govern the control of the signal control line circuits in such manner that these traflic repeater relays when energized connect a suitable source of energy to the line circuit through suitable polarizing means at one end of the stretch, and at the other end of the stretch connect the winding of a signal control relay to the line circuit. The signal control line circuit is thus reversibly connected to the signal control relays at'each of the signal locations, whereby the control of the signals for a particular direction in the stretch is cascaded from one end of the stretch to the other.

I shall describe one form of railway signaling system embodying my invention, and shall then point out the novel features thereof in claims.

In the drawings, Figs. la, ]b, and 1c, when placed side by side in the order named, provide a diagrammatic view of a stretch of railway track equipped with a signaling system according to my invention.

Similar reference characters refer to similar parts in each of the several views.

Referring now to the drawings, there is shown a stretch of railway track extending from the signal ERG at the left-hand or west end of the section, Fig. 1a, to signal 10LG at the right-hand or east end of the section, Fig. 1c, and through which stretch trains may travel in either direction. The stretch of single track between these two signals is divided by conventional insulated joints into a plurality of track sections, namely, sections 3T, 4T, ST, and 6T. Each of the sections is provided with suitable occupancy detecting means, here shown as a direct current neutral track circuit including a track battery connected across the rails at one end of the section and a track relay connected across the rails at the other end of the section, the track batteries being designated by the reference character TB preceded by the number of the section, and the track relays being designated by the reference character TR preceded by the number of the section. These track circuits are of the conventional type in which the track relays associated therewith normally have their contacts picked up, but which release their contacts during the time that any portion of a train occupies the associated section.

A first set of wayside signals, governing trafiic movements in a first direction, and a second set of wayside signals, governing traffic movements in the opposite direction, are provided for governing moves into, through and out of the stretch of track, the wayside signals 4RG and 10LG being considered as entering signals for the single track stretch, while the signals 4LG and 10RG may be considered as leaving signals for the stretch of single track. A single pair of intermediate signals in the stretch, namely, signals 78 and 98, is provided, although it will be seen from the subsequent description that more than one set of intermediate signals may be provided in accordance with my invention.

Although the wayside signals may be of any one of the conventional types, they are herein shown as being of the color light type, each signal having a green, yellow, and red lamp, which, when lighted, indicate proceed, caution, and stop, respectively.

Although not shown herein, the section of track extending between the entering and leaving signals at each end of the single track stretch, for example, the section 3T extending between signals 4RG and 4LG, may comprise a portion of an interlocking in which converging switches or crossovers are arranged to direct traflic movements onto the stretch of single track including the track sections 4T and ST. However, the arrangement has been shown in the simplest possible manner, in which no converging tracks are shown for the entering sections.

It will be assumed for purposes of clarity that the entering and leaving signals at each end of the single track stretch are governed by the operation of a manually controllable lever located at the associated end of the stretch under the control of an operator located nearby, and which may or may not be included as a portion of a conventional interlocking machine. However, it will be obvious to those skilled in the art that the arrangement may be equally as well controlled through the medium of any one of the remote control arrangements known in the art, such as, for example, centralized traffic control systems of the type shown in Letters Patent of the United States No. 2,229,249 issued on January 21, 1941, to Lloyd V. Lewis for'Remote Control Systems.

As shown herein, the signals at each end of the stretch traffic can be set up in a particular direction.

4 are governed by lever-type controllers, such as the lever 48L at the left-hand end of the stretch, and the lever IOSL at the right-hand end of the stretch, which may be levers of the type provided in the usual type of railway interlocking machine. The manner of operation of these levers for governing traflic movements into the stretch will be described subsequently.

In addition, a traflic lever 410FL is shown on Fig. 1a at the left-hand end of the stretch, for governing the direction of trafiic movement through the stretch. As pointed out above in connection with the control of the entering and leaving signals, it will be obvious to those skilled in the art that the lever 4-10FL for governing the direction of traffic in the single track stretch may be readily replaced by any one of several arrangements, includin an arrangement in which the lever 4-10FL is replaced by the contacts of a relay governed by remote control by a code system of the type described in the aforementioned Lewis patent. The trafiic control may also be of the type in which tratfic levers are provided at each end of the single track stretch, requiring cooperation between the operators at each end of the stretch before However, the preferred form of my invention is that in which the tratfic direction is controlled solely from one end of the stretch and it is this form that is shown in the drawings.

At each of the signal locations shown on the drawings, there is provided a source of low voltage direct current energy for the energization of circuits other than the track circuits. This source, which is not shown, is identified by the reference characters B and N designating the positive and negative terminals, respectively. The contacts of relays which are slow in operating are designated by an arrow therethrough, the direction of the arrow indicating the direction of slow operation, for example, a downwardly directed arrow indicating that the contact is associated with a relay which is slow in releasing.

Considering now the apparatus which is located at the left-hand or west end of the single track stretch, this apparatus includes the signal lever 4SL previously mentioned, and the trafiic lever 4-10FL previously mentioned, which may or may not be included as a part of a conventional railway interlocking machine. These levers are provided with contacts which are closed when the lever occupies various positions, as indicated by the reference within the conventional contact symbol. The traffic lever 4-10FL has a left and a right position, also referred to as normal and reverse positions, respectively, and the signal lever 4SL has a normal or center position and in addition thereto a left and a right position, as indicated symbolically on the drawings. The apparatus also includes a signal locking relay 4RASR which is governed in such manner as to be picked up only when signal 4RG is at stop, either following the expiration of a time interval determined by a time element relay 4RTER, which is provided with contacts which are operated following a predetermined time interval after energization of the relay, or following the occupancy of section 3T. A polar tratfic relay 4RFR is provided, in a polar trafiic circuit to be subsequently described, and a tratfic repeater relay 4WFR is provided which is governed in part by a contact of the polar tratfic relay 4RFR. The signals 4LG and 4RG are governed by circuits including contacts of local signal control relays 4LHR and 4RHR, which in turn are governed by the signal lever 4SL and by signal control relays 4LHDR and 4RHDR.

The signal control relays 4LHDR and 4RHDR are of the retained neutral type of polarized relay, as indicated by the shading of the relay coil symbol. Such relays are provided with neutral contacts arranged in such manner that these contacts will not release during the reversal of polarity of energy supplied to the winding of the relay. Relay 4RFR, as well as the other polar relays in the trafiic control circuit, is of the magnetic stick type. That is, its contacts remain in the position to which they were last operated, even though the relay is deenergized, until the relay is energized by current flowing in the opposite direction through the windings.

At the right-hand or east end of the stretch, shown in Fig. 1c, the apparatus is similar to that shown at the lefthand or west end of the section, with the exception that no tratfic lever is provided at this end.

At the intermediate location shown in Fig. 1b, there are provided a traflic relay 7-9FR energized from a line circuit extending between the intermediate location and each of the end locations of the stretch, a signal control relay for each of the intermediate signals, namely, relays 7HDR and 9HDR, and a traffic repeater relay for each of the intermediate signals, namely, relays 7FPR and 9FPR.

The apparatus is shown in its normal condition, with the entering and leaving signals for the single track stretch at each end thereof shown at stop, and with the traffic control circuit energized in such manner as to permit trafiic movements from west to east, or left to right.

At this time, the trafiic control circuit for energizing the tralfic relays 4RFR, 7-9FR, and IOLFR is energized by a circuit which may be traced from terminal B through a reverse contact a of lever 4-10FL, over front contact a of relay 4RASR, front contact b of relay 3TR, through the upper winding of relay 4RFR, over front contact a of relay 4TR, through the upper winding of relay 7-9FR, front contact 0 of relay STR, through the upper winding of relay ltlLFR, front contact b of relay 6TR, front contact a of relay ltlLASR, front contact b of relay LASR, front contact 0 of relay 6TR, the lower winding of relay IOLFR, front contact d of relay STR, the lower winding of relay 7-9FR, front contact b of relay 4TR, the lower winding of relay 4RFR, front contact c of relay 3TR, front contact b of relay 4RASR, and through a reverse contact 0 of lever 410FL to terminal N. With the line circuit energized in this manner, the

contacts of each of the trafiic relays 4RPR, 7-9FR, and

IGLFR will be operated to their normal or left-hand positions as shown.

Relay tRASR is energized at this time by a circuit which may be traced from terminal B through a contact c of the signal lever 45L, back contact a of relay ARHR, front contact 0 of relay 4RASR, and through the winding of relay 4RASR to terminal N. Similarly, relay IOLASR at the east end of the stretch is energized by a circuit which may be traced from terminal B at a contact c of signal lever IOSL, over back contact a of relay lltlLI-IR, front contact 0 of relay lOLASR, and through the winding of relay ltlLASR to terminal N. Relays lLHR, 4RHR, IORHR, and ltlLHR are deenergized at this time,and establish obvious circuits for supplying energy to the red lamp R of the signalswith which they are associated.

The traflic repeater relay 10EFR at the east end of the stretch is energized at this time by a pickup circuit including normal contact b of traffic relay lltlLFR, front contact e of track relay 6TR and front contact d of relay ltlLASR. A stick circuit for this relay is also completed at this time over normal contact b of trafiic relay ltlLFR and front contact a of relay ltlEFR.

At the intermediate signal location, relay 9HDR is energized by energy supplied over the signal control line circuit extending between the intermediate location and the east end of the stretch, this circuit including back contacts a and b of relay 7FPR, front contacts a and b of relay STR, front contacts b and c of relay IOEFR, and back contacts b and c of relay ltlRl-IR. The circuit is arranged so that at this time, with the contacts b and c of relay ltlRHR released, the polarity of the energy supplied to the winding of relay 9HDR will be such that 6 the polar contacts of relay 9HDR will be operated to their reverse position. At this time, therefore, signal 98 will have its yellow lamp energized over the circuit including front contact a and reverse contact b of relay 9HDR, so that signal displays a yellow or caution aspect."

With relay 9HDR energized, a pickup circuit is closed for relay 9FPR at this time, which circuit may be traced from terminal B at normal contact a of relay 7-9FR, over front contact 0 of relay 9HDR, back contact 0 of relay 7FER, and through the winding of relay 9FPR to terminal N. With relay 9FPR energized, its front contact a establishes a stick circuit for this relay including normal contact a of relay 7-9FR, and its back contact b interrupts the control circuit for relay 7FPR to provide a cross-check against the possibility of both of the tratfic repeater relays being picked up at the same time.

4 With contacts c and d of relay 9FPR up, the winding of relay 7HDR is not supplied with energy, and its neutral contacts are released. Back contact d of relay 7HDR establishes the circuit for supplying energy to the red lamp of signal 78, so that this signal displays a stop aspect at this time.

Energy is supplied to the signal control line circuit extending between the intermediate location and the west end of the stretch at this time to energize the winding of relay 4RHDR, the circuit including front contacts of and e of relay 9HDR, front contacts c and d of relay 9FPR, front contacts 0 and d of relay 4TR, and back contacts b and c of relay 4WFR. With contacts d and e of relay 9HDR picked up, the polarity of the energy supplied to the winding of relay 4RHDR at this time is such that the polar contacts of the relay are operated to their normal position.

It will now be assumed that a train movement is to be made from west to east, or left to right, so that the signals 4RG, 9S, and 10RG must display suitable aspects to permit the train to enter, move through, and leave the single track section. Accordingly, the operators at each end of the stretch will position their respective signal levers t0 the right, to clear the corresponding signals. Since the direction of traffic within the single track stretch is already set up for traffic movements from left to right, the lever 4-10FL will remain in its right-hand position.

When the signal lever 10SL is moved to its right-hand position, a circuit is established for energizing relay IORHR, which circuit may be traced from terminal B at front contact a of relay 6TR, over contact b of lever 10SL closed in the right-hand position, front contact a of relay 10RHDR, and the winding of relay 10RHR to terminal N. Relay IORHDR may be a retained neutral type of relay governed by traffic conditions in advance of signal 10R, and at this time it will be assumed that traflic conditions in advance of signal IORG are such that the contacts of relaylORHDR are picked up and the polar contacts are operated to their left-hand or normal position. Accordingly, when relay 10RHR picks up, the circuit is established including front contact a of relay MRI-IR and normal contact b of relay 10RHDR for supplying energy to the green lamp G of signal 10RG, so that this signal displays a clear aspect.

When contacts b and c of relay IORHR pick up, the energy supplied to the signal control line circuit extending between the right-hand end of the single track stretch and the intermediate location is pole-changed, and, accordingly, the polar contact b of relay 9HDR is operated. from its right-hand or reverse position to its left-hand or normal position. Since relay 9HDR is of the retained neutral type, the neutral contacts of the relay will not release during this pole-changing interval. When contact b of relay HDR closes in its normal position, the circuit for supplying energy to the yellow lamp Y of signal 98 is interrupted and a circuit for supplying energy 7 to the green lamp G of this signal is established, so that signal 95 displays a green or clear aspect.

At the left-hand or west end of the section, when signal lever 4SL is moved to its right-hand position, a circuit is established for energizing relay 4RHR, which circuit may be traced from terminal B at front contact a of track relay 3TR, over contact a of signal lever 4SL, closed in the right-hand position, normal contact a of polar traflic relay 4RFR, back contact a of time element relay 4RTER, front contact a of relay 4RHDR, and through the winding of relay 4RHR to terminal N. Since signal control relay 4RHDR is energized by energy of normal polarity supplied thereto over the line circuit extending between the left-hand end of the stretch and the intermediate location, the neutral contacts of relay 4RHDR will be picked up and the polar contacts operated to their normal or lefthand position at this time. When contact b of relay 4RHR picks up, a circuit is established for supplying energy to the green lamp G of signal 4RG, while the circuit for supplying energy to the red lamp R of this signal is interrupted.

From the foregoing, it will be seen that at this time the signals 10RG, 9S, and 4RG will all display green or clear aspects for a train movement from left to right through the stretch.

When signal lever 4SL is operated to its right-hand position, the circuit including contact of this lever for energizing relay 4RASR is interrupted, and this circuit is further interrupted at back contact a of relay 4RHR when this relay picks up to clear signal 4RG. Contact 0 of relay 4RASR' further interrupts the stick circuit when the relay releases.

The release of front contacts a and b of relay 4RASR interrupts the trafiic control line circuit, so that traffic relays 4RFR, 7-9FR, and 10LFR are deenergized, and their contacts cannot be reversed at this time, even if lever 4-10FL should be inadvertently operated to its left-hand position. Thus the traffic relays are immobilized when a signal has been cleared to permit an oncoming train to enter the single track stretch.

It can also be seen that, with the traffic circuit deenergized, contact a of relay 10LFR must remain in its normal position, and even if an attempt were made to clear signal 10LG for an opposing train, the control circuit for relay 10LHR could not be completed. Movement of lever 10SL to its left-hand position would cause contact 0 of this lever to interrupt the stick circuit for relay 10LASR, and this relay would release. Contacts a and b of relay 10LASR would further interrupt the traffic control circuit to no effect at this time. Contact d of relay 10LASR would interrupt the pickup circuit for relay IOEFR, but this relay would remain energized over its previously traced stick circuit.

If, before the eastbound train passes signal 4RG, the operator restores signal lever 4SL to its normal position, relay 4RHR will release to cause signal 4RG to display its stop aspect. However, relay 4RASR cannot pick up at this time until after time element relav 4RTE-R has completed its operating cycle. Relay 4RTER will be energized over thecircuit including contact c of lever ASL, back contact a of relay 4RHR, and back contact 0 of relay 4RASR. After a suitable time interval, the contacts of relay 4RTER will pick up, and front contact 11 of this relay will complete the circuit for energizing relay 4RASR.

When relay 4RASR picks up, its contact c reestablishesthe stick circuit-for the relay, and cuts off the supply of energy to the time element relay, while front contacts a and b reclose the trafiic circuit.

It is apparent that, if the approaching train has insufficient time to come to a stop before passing signal 4RG. the train will overrun the signal at stop, before the time element relay has operated to reenergize relay 4RASR. Should this situation occur, the train will shunt track 8 relay 3TR, and its contacts b and 0 will interrupt the traffic control circuit.

It is clear from the foregoing that the system is arranged so that, after once having cleared a signal for a train to enter the stretch, the traffie circuit cannot be disturbed until conditions are restored to normal, that is, with the stretch unoccupied and the entering signals at stop.

Assuming, however, that signal 4RG is permitted to remain cleared for the approaching eastbound train, when the train passes signal 4RG and enters the single track stretch, the track relay 3TR is released and its front contact a interrupts the circuit for energizing relay 4RHR, so that, as a result, relay 4RHR releases its contacts and its contact b interrupts the circuit for supplying energy to the green lamp G of signal 4RG and reestablishes the circuit for supplying energy to the red lamp R of the signal to thereby display a red or stop aspect behind the train moving through the single track stretch. The release of contacts b and c of relay STR interrupts the polarized traffic circuit, so that the polar tralfic relays cannot be operated at this time with the train occupying the stretch.

It will be assumed that the operator at the left-hand end of the stretch now restores the signal layer 4SL to its center or normal position, and accordingly a circuit is established for picking up relay 4RASR, which circuit includes contact 0 of lever 4SL, back contact a of relay 4RHR, back contact at of relay 3TR, and the winding of relay 4RASR. When relay 4RASR picks up, its front contact c reestablishes the stick circuit for this relay. The contacts a and b of relay 4RASR are now closed in the traflic circuit, but the circuit remains interrupted since relay 3TR is released because of the entry of the train into the single track stretch.

When the train in question enters section 4T, the contacts of relay 4TR are released, front contacts a and b of this relay further interrupting the tratiic control circuit, and front contacts c and d of the track relay interrupting the signal control line circuit, so that relay 4RHDR at the left-hand end of the stretch is deenergizcd. The release of contact a of relay 4RHDR will prevent the reclearing of signal 4RG for a following train while the eastbound train is still occupying any portion of sec tion 4T.

With the train wholly contained within section 41, track relay 3TR will again pick up, and its contacts b and c will be closed in the traffic control circuit, but this circuit remains deenergized, since it is opened at front contacts a and b of relay 4TR.

When the eastbound train passes signal 98, track relay STR will be released, and its front contacts a and b will interrupt the signal control circuit which supplies energy at this time to the winding of relay 9HDR, with the result that the neutral contacts of relay 9HDR will release.

The release of contact a of relay 9HDR interrupts the circuit for supplying energy to the green lamp G of signal 9S and establishes an obvious circuit for supplying energy to the red lamp R of this signal, to thereby cause signal to display a red aspect behind the eastbound train. The release of contacts d and e of relay 9HDR in the signal control circuit for supplying energy to the signal control relay 4RHDR at the left-hand end of the stretch will cause the circuit to be pole-changed, but no effect will result at this time since this circuit is open at contacts c and d of relay 4TR.

Contact 0 of relay 9HDR is also open at this time in the pickup circuit for the traffic repeater relay 9FPR, but this relay remains energized over normal contact a of the polar traflic relay 7-9FR, front contact a of relay 9FPR, and back contact 0 of relay 7FPR.

When the rear of the eastbound train vacates section 5T, track relay 4TR will pick up and its contacts a and g. b will be closed in the polarized trafiic circuit, but this circuit remains open since front contacts a and d of relay 5TR are released at this time.

When contacts and d of relay 4TR pick up, the circuit is reestablished for supplying energy to the signal control relay 4RHDR at the left-hand end of the stretch, but, as previously pointed out, relay 9I-IDR- is released at this time, so that the polarity of the energy supplied to relay tRI-IDR is reversed. Accordingly, the polar contact b of the signal control relay 4RHDR will be operated to its reverse position, and the neutral contact a of relay 4RHDR will be picked up.

At this time, the operator at the left-hand end of the stretch may reclear signal 4RG for a following train movement, by operating signal lever 48L to its righthand position. The relay 4RHR will be energized by the circuit originally traced, but whencontact b of this relay picks up, it will establish a circuit including the reverse contact b of relay 4RHDR for lighting the yellow lamp Y of signal 4RG, thereby causing signal 4RG to display a yellow or caution aspect, indicating that a preceding train is occupying the single track stretch.

Again considering the eastbound train moving through section 5T, it will be now assumed that this train proceeds past signal IORG and enters track section 6T. The release of contact a of track relay 6TR will interrupt the circuit previously traced for energizing relay ltlRHR, so that contact a of this relay will interrupt the supply of energy to the green lamp G of signal RG and establish an obvious circuit for supplying energy to the red lamp R of this signal.

Front contacts b and c of track relay 6TR further interrupt the traffic control circuit, and contact e of track relay 6TR in the pickup circuit for the traflic repeater relay IOEFR will be opened, but relay 10EFR remains picked up at this time by the stick circuit including normal contact b of the traflic relay ltlLFR, and front contact a of the trafiic repeater relay IOEFR.

When the rear of the eastbound train vacates section 5T, track relay STR will again pick up, and its front contacts a and b will reestablish the circuit for supplying energy to the winding of relay 9HDR. However, at this time, relay lltlRHR is released so that the polarity of the energy supplied to the signal control line circuit is reversed, With the result that relay 9HDR will be supplied with energy such that the polar contacts of this relay will be operated to their reverse position, and the neutral contacts of the relay will be picked up. Accordingly, the circuit as shown on the drawing will be established for supplying energy to the yellow lamp Y of signal 93, thereby causing this signal to display a caution aspect indicating that the next signal is at stop. The traffic control circuit remains interrupted at this time even though front contacts c and d of relay STR are again closed, since front contacts b and c of relay 6TR remain released. When the train passes out of section 6T, track relay 6TR will again pick up, and contacts b and c of the track relay will reestablish the polarized traffic circuit.

It will be assumed that when the train moves past signal ltlRG, the operator at the right-hand end of the stretch will restore the signal lever ltlSL to its center or normal position, thereby further interrupting the circuit for energizing relay lltlRHR. The presence of the eastbound train in advance of signal 10RG will cause the relay ltlRHDR to be released, so that its contact a further interrupts the supply of energy to the home signal control relay IORHR. After the eastbound train has proceeded a sufficient distance beyond signal ltlRG, relay IORHDR will again become picked up, and at this time, the signal lever 10SL may again be operated to its right-hand position to clear signal 10RG for a second or following train.

It will be apparent at this time from the foregoing that the apparatus shown operates to govern the movements it) of trafiic into and through the single track stretch in the conventional manner, in which each of the wayside signals when passed by the train presents a red or stop aspect for a following train, and when the train in question has proceeded a sufficient distance in advance of the signal, the signal again may be cleared to permit a following movement. The system as it now stands with the eastbound train having proceeded through the single track stretch is in the condition as shown in the draw ings and as initially described.

it will now be assumed that, with the system in the condition as shown, it is desired to prepare the stretch 'for the movement of a Westbound train through the single track stretch from right to left.

At this time, the operator at the left-hand or west end of the stretch will operate the trafi'ic lever 4-10FL from its right-hand to its left-hand position in accordance with the direction in which trafiic is to move through the stretch. When lever 410FL is operated from its right- .hand to its left-hand position, the contacts a and c of the lever are opened, and contacts b and d are closed. As a result, the traflic relays 4RFR, 79FR, and ltlLFR are now energized by a circuit which may be traced from terminal B at contact b of lever 4-10FL, over front contact b of relay 4RASR, front contact 0 of relay 3TR, through the lower winding of relay 4RFR, over front contact b of relay 4TR, through the lower winding of relay 7-9FR, over front contact d of relay STR, through the lower winding of relay ltlLFR, over front contact '0 of relay 6TR, front contact b of relay IOLASR, front contact a of relay ltlLASR, front contact b of relay 6TR, through the upper winding of relay ltlLFR, front contact c of relay STR, the upper winding of relay '7-9FR, front contact a of relay 4TR, the upper winding of relay 4RFR, front contact 11 of relay 3TR, front contact a of relay 4RASR, and through contact d of lever 4-10FL to terminal N. It will be seen that the polarity of the energy supplied to the line circuit is reversed so that the contacts of relays 4RFR, 7-9FR, and ltlLFR will each be operated from the normal to the reverse position. When contact b of relay 4RFRcloses in the deverse position, a circuit is established for energizing relay WVFR, which circuit may be traced from terminal B at reverse contact b of relay iRFR, over front contact e of relay STR, front contact d of relay 4RASR, and through the winding of relay 4WFR to terminal N. When relay 4WFR picks up, its front contact a establishes a stick circuit including this contact and the reverse contact, b of relay tRFR to maintain relay 4WFR energized. At the intermediate signal location, the reversal of relay 7-9FR will interrupt the circuit for supplying energy to trafiic repeater relay 9FPR, so that the contacts of this relay are released.

At this time, with the contacts of relay 4WFR picked up at the left-hand or west end of the stretch, and the contacts of trafiic repeater relay 9FPR at the intermediate location having been released, a circuit is established for energizing the winding of the signal control relay 7HDR, which circuit may be traced from terminal B at back contact c of relay 4LHR, over front contact 0 of relay 4WFR, front contact d of relay 4TR, back contact at of relay 9FPR, through the winding of relay 7HDR, over I back contact 0 of relay 9FPR, front contact 0 of relay -iTR, front contact b of relay 4WFR, and back contact b of relay 4LHR to terminal N. Accordingly, relay 7HDR will have its polar contacts operated to their reverse position and the neutral contacts picked up. With neutral contact d of relay 7HDR picked up and polar contact e in its reverse position, the supply of energy for the red lamp R of signal 78 is interrupted and a circuit is established for supplying energy to the yellow lamp Y of signal 75 so that this signal displays a yellow or caution aspect.

When front contact 0 of relay 7HDR closes, a circuit is established for energizing the winding of relay 7FPR,

which circuit may be traced from terminal B at reverse contact a of relay 7-9FR, over front contact of relay 7HDR, back contact B of relay 9FPR, and through the winding of relay 7FPR to terminal N. When the contacts of relay 7FPR pick up, front contact d of this relay establishes a stick circuit including the reverse contact a of relay 7-9FR and back contact b of relay 9FPR to maintain relay 7FPR energized even though front contact c of relay 7HDR may be opened as a result of the subsequent train movement past signal 75.

At the right-hand or east end of the stretch, the reversal of contact B of polar traffic relay 10LFR interrupts the circuit including this contact and front contact a of relay 10EFR for maintaining relay IOEFR energized, and as a result the contacts of this relay release. With contacts b and c of relays IOEFR released at the east end of the stretch, and contacts a and b of relay 7FPR at the intermediate location picked up, a circuit is established for supplying energy to the winding of signal control relay IOLHDR at the right-hand or east end of the stretch. This circuit may be traced from terminal B at front contact b of relay 7HDR, over front contact a of relay 7FPR, front contact a of relay STR, back contact b of relay IOEFR, through the winding of relay IOLHDR, back contact 0 of relay 10EFR, front contact b of relay TR, front contact b of relay 7FPR, and front contact a of relay 7HDR to terminal N. Accordingly, the neutral contacts of relay LHDR will be picked up and the polar contacts of this relay will be operated to their normal or left-hand position.

When the contacts a and b of relay 7FPR at the .inter mediate location are picked up, and the contacts b and c of relay 10EFR at the right-hand end of the stretch are released, the supply of energy to the winding of relay 9HDR at the intermediate location is cut off, and the neutral contacts of this relay release. Back contact a of relay 9HDR then establishes a circuit for supplying energy to the red lamp R of signal 98.

At this time, it will be seen that the signal control line circuits for the stretch have been reversed in their energization, so that energy is supplied from the lefthand or west end of the stretch over the signal line circuit to energize the signal control relay for the westbound intermediate signal, that is, signal 7S, and this signal displays a yellow or caution aspect, since signal 4LG is at stop at this time. Additionally, the signal control line circuit extending between the intermediate location and the right-hand or east end of the stretch is energized at the intermediate-location to thereby energize the signal control relay at the east end of the stretch. The signal control relay 9HDR which governs the eastbound intermediate signal 98 is deenergized so that this signal displays a red or stop aspect. The stretch is now prepared for the clearing of the signals 10LG and 4LG to permit a train to move into and through the single track stretch. When the operator at the right-hand end of the stretch operates signal lever 10SL to its left-hand position, a circuit is established for energizing the local signal control relay 10LHR, which circuit may be traced from terminal B at front contact a of relay 6TR, over contact a of lever 10SL closed in the left-hand position, over a reverse contact a of relay 10LFR, back contact a of time element relay IOLTER, front contact a of signal control relay IOLHDR, and through the winding of relay IOLHR to terminal N.

When relay 10LHR picks up, its front contact b establishes a circuit including the normal contact b of contact c of the lever 10SL is open when this lever is in its left-hand position, and the circuit is further interrupted at back contact a of relay IOLHR, so that relay 10LASR releases. The release of contacts a and b of relay 10LASR interrupts the traflic control circuit, so that the position of the contacts of the polar traflic relays 4RFR, 7-9FR, and 10LFR cannot be changed at this time with a signal cleared for a train to move into the stretch.

At the left-hand or west end of the stretch, when the operator rnoves signal lever 4SL to its left-hand position, a circuit is established for energizing the local signal control relay 4LHR, which circuit may be traced from terminal B at front contact a of relay STR, over contact b of lever 43L, closed in the left-hand position, over front contact a of relay 4LHDR, and through the winding of relay 4LHR to terminal N. When contact a of relay 4LHR picks up, it establishes a circuit for supplying energy to the green or yellow lamp of signal 4LG, depending upon the position of polar contact b of relay 4LHDR, which is governed by the trafiic conditions in advance of signal 4LG. When contacts b and c of relay 4LHR pick up, the energy supplied to the signal control line circuit is pole-changed thereby, so that the relay 7HDR at the intermediate location will have its polar contacts operated to their normal position, in which contact e interrupts the supply of energy to the yellow lamp Y of signal 78 and establishes a circuit for supplying energy to the green lamp G of signal 78.

It will be seen that the westbound signals in the stretch now display aspects which will permit the westbound train to move into and through the stretch.

Operation of the signal locking relay IOLASR under the condition in which the signal is restored to stop before the approaching train can accept the signal is similar to that previously described for relay 4RASR, and a detailed description of such operation is accordingly deemed unnecessary.

When the westbound train passes signal 10LG at the east end of the stretch, relay 6TR will release its contacts, and contact a of this relay will interrupt the supply of energy to the winding of local signal control relay 10LHR, so that this relay releases, thereby interrupting the circuit for supplying energy to the green lamp G of the signal and establishing the circuit for lighting the red lamp R of the signal to provide a stop aspect behind the westbound train. Contacts b and c of relay 6TR release to further interrupt the tratfic control circuit so that the polar traflic relays cannot be operated at this time. With relay 10LHR released, and contact d of the track relay 6TR released, a circuit is established for encrgizing relay 10LASR when the operator restores the signal control lever 10SL to its center or normal position. This circuit may be traced from terminal B at contact 0 of lever 10SL, over back contact a of relay IOLHR, back contact d of relay 6TR, and through the winding of relay 10LASR to terminal N. When relay 10LASR picks up, its front contact 0 establishes a stick circuit for the relay, so that relay 10LASR will remain energized after contact d of relay 6TR again picks up.

The closing of front contacts a and b of relay IOLASR in the traffic circuit will not reestablishthe circuit at this time, since, as previously pointed out, the circuit is opened at front contacts b and c of relay 6TR.

When the westbound train enters section 5T, relay STR will be released and its contacts a and b will interrupt the signal control line circuit extending between the intermediate signal location and the eastern end of the single track stretch, to thereby release the contacts of signal control relay 10LHDR located at the east end of the stretch. Contacts c and d of relay STR release to further interrupt the tratfic control circuit so that when the rear of the train vacates section 6T, and the contacts b and c of relay 6TR are again picked up, the trafiic 13 l control circuit will remain open with the result that the tratlic control relays cannot be energized to reverse their contacts. Y

When the westbound train passes signal 75, track relay 4TR is shunted and its contacts release, with contacts a and b of the relay further interrupting the trafiic control circuit, and contacts and d interrupting the signal control line circuit to thereby cause the release of signal control relay 7HDR. When contact d of relay 7HDR releases, it interrupts the supply of energy to the green lamp G of signal 78 andestablishes a circuit for supplying energy to the red lamp R of this signal. Contact 0 of relay 7HDR releases in the pickup circuit for relay 7FPR, but as previously explained this relay remains energized at this time by the stick circuit including front contact d of relay 7FPR and back contact b of relay 9FPR, so that relay 7FPR remains energized.

When the rear of the westbound train vacates section T, contacts a and b of the relay STR pick up to reestablish the supply of energy to the signal control line circuit and to energize the winding of relay IOLHDR at the east end of the stretch. However, at this time con tacts a and b of relay 7HDR are released, so that the supply of energy to the line circuit is pole-changed with the result that the polar contacts of relay IOLHDR will be operated to their reverse position. If, at this time, the operator at the east end of the stretch desires to clear signal LG for a following westbound train, he can operate signal lever 10SL to its left-hand position, whereupon the local signal control relay IOLHR will be energized by the circuit previously described and its contact b will pick up to close the circuit including reverse contact b of relay IOLHDR to light the yellow lamp Y of signal 10LG, thereby denoting to the following train that the next signal is at stop.

When the westbound train passes signal 4LG, track relay 3TR will be released and its contact a will interrupt the supply of energy to the winding of the local signal control relay 4LHR, so that contact a of this relay will interrupt the supply of energy to the green lamp G of signal 4LG and establish a circuit for supplying energy to the red lamp R of this signal. The release of contacts b and c of relay 3TR will further interrupt the traffic control circuit so that the traffic control relays cannot be energized at this time. Contact e of track relay 3TR opens in the pickup circuit for the traffic repeater relay 4WFR, but this relay remains energized through the stick circuit which includes front contact a of the relay and reverse contact b of relay 4RFR, with the result that the traflic repeater relayremains picked up.

When the rear of the westbound train vacates section 4T, track relay 4TR will pick up and its contacts c and d will again be closed in the signal control line circuit so that energy is again supplied to the winding of signal control relay 7HDR. However, at this time, contacts b and c of relay 4LHR are released so that the polarity of the energy supplied to the winding of relay 7HDR is reversed with the result that the contact a of this relay is operated to its reverse position, thereby causing signal '78 to display a yellow aspect.

When the rear of the train vacates section 3T, track relay STR will pick up and its front contact a in the control circuit for the local signal relays will again be closed, but it will be assumed that the operator at the left-hand or west end of the stretch has restored the signal lever 48L to its normal position, so that the circuit for supplying energy to the local signal control relays will be interrupted at this point. At this time, with contacts b and c of relay 3TR again picked up, the trafiic control circuit is again established, and energy is supplied to the traffic relays iRFR, 7-9FR, and 10LFR. However, this energy is of such polarity that the contacts of the traflic relays will remain in their reverse position since lever 4-10FL is still considered to be in its left-hand position for esi 14 tablishing traflic in the westward direction through the single track stretch.

The system is now restored to the condition in which the single track stretch has the trafiic direction for westbound trains established therein, but with the entering signal 10LG and the leaving signal 4LG both at stop as was previously described.

The operator at the west end of the stretch may now restore trafiic conditions to their original condition in which the single track stretchis conditioned for eastbound traiiic by operating the traffic control lever 410FL from its left-hand to its right-hand position. When this is accomplished, the contacts b and d of the lever 4-10FL are opened and contacts a and c are closed, so that the supply of energy to the traflic control circuit is restored to its normal polarity, and since the contacts of all of the track relays involved in the single track stretch, in addition to the contacts of the signal locking relays, are picked up, energy will be supplied through the windings of the polar trafiic relays to cause these relays to operate their contacts to their left-hand or normal position as shown in the drawing.

When contact b of relay 10LFR at the east end of the stretch operates to its normal position, it closes the circuit for energizing the trafiic repeater relay IOEFR, this circuit extending from terminal B at normal contact b of relay EOLFR, through front contact e of relay 6TR, front contact d of relay IOLASR, and the winding of relay lltlEFR to terminal N. When this relay picks up, its front contact a establishes a stick circuit including the normal contact b of relay ltlLFR to maintain the relay energized.

At the intermediate signal location, the operation of contact a of the polar traffic relay 7-9FR to its normal position interrupts the supply of energy to the winding of relay '7FPR, so that the contacts of this relay release. With contacts a and b of relay 'iFPR released, energy is now supplied to the winding of relay 9HDR, by a circuit including contacts b and c of relay I'ORHR, front contacts b and c of relay WEFR, front contacts a and b of relay STR, and back contacts a and b of relay 'IFPR.

With the contacts of relay ltlRI-IR released, the polarity of the energy supplied to the winding of relay 9HDR is such that its polar contacts will be operated to their reverse position. The neutral contact a of relay 9HDR will be picked up, and, accordingly, a circuit is established for supplying energy to the yellow lamp Y of signal 98. Additionally, when contact c of relay 9HDR picks up, a circuit is established for energizing traflic repeater relay QFPR, which circuit includes normal contact a of relay 7-9FR, front contact 0 of relay 9HDR, back contact 0 of relay TFPR, and the winding of relay QFPR. When the contacts of relay 9FPR pick up, front contact a of this relay establishes a stick circuit including normal contact a of relay 7-9FR and back contact 0 of relay 7FPR to maintain the relay energized.

The contacts c and d of relay 9FPR pick up to thereby interrupt the connection of the winding of relay 7HDR to the signal control line circuit, and energy is supplied to the winding of relay 4RHDR at the. west end of the stretch at this time by the circuit including front contacts d and e of relay 9HDR, front contacts 0 and d of relay 9FPR, front contacts 0 and d of relay 4TR, and back contacts b and c of relay 4WFR, so that relay 4RHDR is energized with energy of polarity such that the polar contacts of the relay are operated to their normal position.

At this time, it will be seen that the apparatus is restored to its original condition as shown on the drawings, with the direction of traffic in the single track stretch set up for train movements from left to right, that is, eastbound.

Summarizing the foregoing description of the arrangements shown on the drawings, it will be apparent that I provide in a railway signaling system of the type arranged to govern movements of traflic in either direction through a single track stretch, a polarized traffic circuit arranged to be supplied with energy of one polarity or the other depending upon the direction in which it is desired to establish traffic movements through the stretch, a polar tratfic relay being provided at each of the signal locations throughout the stretch, and the polar trafiic control circuit being governed by contacts of the track relays to detect occupancy of any portion of the stretch and in addition being governed by the contacts of signal locking relays which check that the signals governing movements into the stretch are at stop, so that the contacts of the trafiic relays may only be operated when the stretch is unoccupied and the signals governing movements into the stretch indicate stop. I provide, in addition to the trafiic control circuit, signal control circuits which are arranged to be selectively energized from one end to the other to thereby govern signal control relays, the direction of energization of these circuits being governed by traffic repeater relays which are in turn governed by contacts of the polar traffic relays and contacts of the signal control relays for the portion of the stretch in advance of each signal. Thus, it will be seen that the signal control circuits are energized in sequence from the selected exit end of the stretch to the entrance end of the stretch, in each case checking that the position of the polar traffic relay corresponds with the designated direction of traffic before energy can be applied to the appropriate signal control circuits.

The feature of employing the trafiic stick relays to check the position of the polar trafiic relays is important, since it prevents the clearing of a signal for a train movement into the stretch unless all of the polar tratfic relays are properly positioned. For example, if one of the traific relays should fail to operate during a traffic reversal, the signal control line circuits would be energized in sequence from the selected exit end to the location of the unoperated trafiic relay, but the signal control circuits from this location to the selected entrance end would be deenergized, so that the entering signal could not be cleared. Thus there is prevented the possibility that, due to faulty operation of the traflic relays, signals could be cleared for opposing train movements.

It will be apparent to those skilled in the art that any number of intermediate signals may be employed in tl stretch, only a single intermediate location being shown for the sake of simplicity, but other intermediate signal locations being governed in an identical manner, by providing additional polar trafiic relays and trafiic stick relays, together with the associated signal control circuits and signal control relays. those skilled in the art that the manner of control of energization of the polarized trafiic control circuit may be varied in accordance with conditions, to provide control of this circuit from a single end of the stretch or from both ends of the stretch either by the operation of levers or other manual switching devices under the control of operators located at each end of the stretch or at one end of the stretch, or by the use of suitable remote control systems, for controlling either or both ends of the stretch.

Although I have herein shown and described only one form of railway signaling system embodying my invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a railway signaling system for governing train movements in either direction over a single track stretch of railway divided into a plurality of track sections, an intermediate signal located within said stretch at the junction of two of said sections for governing traffic in a given direction, a signal control relay for governing said signal, a signal control circuit extending in each direction from said intermediate signal location, traflic direction It will also be apparent to selecting means, a tratfic repeater relay, means governed by said traffic direction selecting means for at times supplying energy to said signal control relay over the signal control circuit extending in advance of said intermediate signal in accordance with trafiic conditions in advance of said signal, a pickup circuit for said trafiic repeater re lay including a contact governed by said trafiic direction selecting means closed when the direction of traffic corresponds with the direction in which said intermediate signal governs traffic and a contact governed by said signal control relay, a stick circuit for said tratfic repeater relay including said contact governed by said tratfic direction selecting means and a front contact of said traffic repeater relay, and means governed by contacts of said trafiic repeater relay and said signal control relay for supplying energy to the signal control circuit extending to the rear of said intermediate signal.

2. In a railway signaling system for governing train movements in either direction over a single track stretch of railway divided into at least two track sections, occupancy detecting means associated with each of said track sections and responsive to the occupied or unoccupied condition of said section, a first and a second intermediate signal located at the junction of said track sections, said first signal governing trafiic movements in a first direction and said second signal governing tratfic movements in a second direction, a first and a second signal control relay and a first and a second traflic repeater relay associated with ,said first and second signals respectively, traffic direction selecting means, a first and a second line circuit extending in opposite directions from said intermediate signals, means including said occupancy detecting means for supplying energy to said first or said second line circuit at the end thereof remote from said intermediate signal according as the direction of traffic is established in said first or said second direction and in accordance with traffic conditions in advance of said signals, a pickup circuit for each of said tratfic repeater relays including a contact governed by said traffic direction selecting means and closed when the selected direction or trafiic corresponds with the direction in which the associated signal governs trafiic movements and a from contact of the associated signal control relay, a stick circuit for said trafiic repeater rclays including said contact of said traflic direction selecting means, each said signal control relay being connected to the associated line.circuit in advance over back contacts of the opposite trafl'ic repeater relay, and means including front contacts of the associated traffic repeater relay for supplying energy in cascade to the line circuit to the rear in accordance with the aspect displayed by the intermediate signal.

3. In a railway signaling-system for governing train movements in either direction over a single track stretch of railway divided into at least two track sections, occupancy detecting means associated with each of said track sections and responsive to the occupied or unoccupied condition of said section, a first and a second intermediate signal located at the junction of said track sections, said first signal governing tratfic movements in a first direction and said second signal governing tratfic movements in a second direction, a first and a second signal control relay and a first and a second tratfic repeater relay associated with said first and second signals respectively, a trafiic relay, means for operating the contacts of said traffic relay to a first or a second position in accordance with. the selected direction of trafiic through said stretch, means for preventing operation of said traffic relay when any portion ,of said stretch is occupied by a train or conditioned to be occupied by a train, a first and a second signal control ine circuit extending from said intermediate signals in said first and second directions respectively,a pickup circuit for said first trafiicrepeater relay including a contact of said traflic relay closed in said first position and a front contact of said first signal control relay, a stick circuit for said first trafiic repeater relay including said contact of said trafiic relay closed in said first position, a pickup circuit for said second traffic repeater relay including said contact of said traffic relay closed in said second position and a front contact of said second signal control relay, a stick circuit for said second traflic repeater relay including said contact of said trafiic relay closed in said second position, means including back contacts of said second and said first trafiic repeater relays for connecting the windings of said first or said second signal control relay to said first or said second signal control line circuits respectively, and means including front contacts of said first and said second traffic repeaters for supplying energy to said second or said first signal control line circuits in accordance with the aspect displayed by said first and said second signals respectively.

4. A stretch of railway track divided into a plurality of track sections, detection means associated with each of said sections and responsive to the occupancy of the associated section by a vehicle or train, a first set of signals, one for each of said sections, for governing the movement of trafiic in a first direction through said stretch, a second set of signals, one for each of said sections, for governing traflic movements in a second direction through said stretch opposite to said first direction, a plurality of polar traflic relays for selectively controlling the operation of said first or said second set of signals, a traflic line circuit for supplying energy to said polar trafiic relays, said traffic line circuit being governed by said detection means, means for energizing said line circuit with energy of one polarity or the opposite polarity in accordance with the direction of traffic movement through said stretch, a signal locking relay associated With each of the signals governing the entrance of a train into said stretch, said signal locking relays being energized only when the associated signals are at stop, said traflic control circuit including front contacts of said signal locking relays, a traific repeater relay associated with each of said signals except the signals governing the entrance of trafiic into said stretch, a signal control relay associated with each of said signals for controlling the aspect displayed by the signal, signal control line circuits extending between each signal location in said stretch, means including back contacts of said trafiic repeater relays for selectively connecting said signal control relays to said signal control line circuits, means including front contacts of said traffic repeater relays for selectively connecting a source of energy to the end of said signal control line circuits at the end opposite to the 18 end to which the signal control relay is connected, and means governed by said tralfic relays and said signal control relays for selectively energizing in cascade said traflic repeater relays corresponding to the established direction of trafiic.

5. In a railway signaling system for governing train movements in either direction over a stretch of single track railway divided into a plurality of sections, occupancy detecting means associated with each of said sections responsive to the occupancy of the section by a train, a first set of wayside signals spaced throughout said stretch for governing trafiic movements through said stretch in a first direction, a second set of wayside signals spaced throughout said stretch for governing tratfic movements through said stretch in a second direction, a signal control relay for each of said signals, a plurality of signal control line circuits, one of said signal control line circuits extending between adjacent signals in said stretch and governed by said ocupancy detecting means associated with the intervening track sections, a traflic relay associated with each of said wayside signals, said traiiic relays having contacts which are'operated to a .first or a second position as the selected direction of trafiic through said stretch is in said first or said second direction respectively, and means for checking the correspondence in position of the contacts of all trafi'lc relays in the stretch before clearing an entering signal for a train movement through the stretch, comprising a traffic repeater relay associated with each of said signals except the entering signals, circuit means for energizing said trafiic repeater relays including front contacts of said signal control relays, means for energizing said line circuits including front contacts of said traffic repeater relays, and means for connecting said signal control relays to the corresponding line circuits including back contacts of said traflic repeater relays, said traffic repeater relays being additionally governed by said traflic relay to be energized when and only when said traflic relays have their contacts operated to a position corresponding to the direction in which the signal associated with the trafilc repeater relay governs trailic movements.

References Cited in the file of this patent UNITED STATES PATENTS 2,154,539 Stoker Apr. 18, 1939 2,271,510 Allen Feb. 3, 1942 2,354,052 Pelikan July 18, 1944 2,586,458 Failor Feb. 19, 1952 

